In the case of detecting a force applied in a three-dimensional space, there occurs a need to independently detect respective axial components of the applied force in the three-dimensional coordinate system expressed by three axes of X, Y and Z. Conventional force detectors generally used convert a stress-strain resulting from an applied force to a quantity of electricity using a strain gauge, etc. to thereby conduct a detection. Ordinarily, there are many instances where a strain gauge is stuck on a strain generative body processed in three dimensions to detect stress-strain in respective directions of X, Y and Z axes of the strain generative body to thereby make a detection of force.
In various industrial equipments with motion including robot, detection of acceleration in the three-dimensional coordinate system is required. Namely, there occurs a need to independently detect respective axial direction components of acceleration in the three dimensional coordinate system represented with three axes of X, Y and Z. Conventional acceleration detectors generally used convert a stress-strain resulting from an acceleration to a quantity of electricity using a strain gauge to thereby conduct a detection. Ordinarily, there are many instances where a strain gauge is stuck on a structure of a cantilever to make a detection of acceleration in a specified direction by a strain due to stress of the cantilever in the same manner as in the above-described force detector.
However, the above-described conventional force detector and acceleration detector have the problem that the structure is complicated and is therefore not suitable for mass production. For example, three sets of cantilevers must be combined in three dimensions in order to detect three axial direction components in an apparatus using a structure of cantilever. Accordingly, there occurs the problem that such an apparatus is not suitable for mass production and becomes costly. Further, because a sensor such as a strain gauge is used in prior art apparatus, there is the problem that measurement accuracy is low.
On one hand, Hall element and magneto-resistance effect element, etc. are known as the magnetism detector. Hall element is generally comprised of a rectangular semiconductor thin plate. When a bias current is caused to flow in a length direction of the semiconductor thin plate to produce a magnetic field in a direction normal to the bias current, an electromotive force proportional to the magnetic field is produced normal to both the bias current and the magnetic force by Lorentz force. By detecting this electromotive force, the magnitude of the magnetic field is recognized. On the other hand, in the case of magneto-resistance effect element, when a magnetic field is applied to the magneto-resistance effect element in which a current is flowing, a passage of carrier is elongated by Lorentz force, resulting in an increase in electric resistance. By detecting this electric resistance, the magnitude of the magnetic field is recognized.
However, Hall element or magneto-resistance effect element as described above has the problem that it is difficult to precisely detect the direction of magnetic field although the magnitude of the magnetic field can be easily detected.